Old records show tsunamis were common

Could a tsunami early-warning system have avoided the loss of life here at the Indonesian city of Banda Aceh? This aerial photograph was taken almost a month after the disaster (Image: Reuters/Australian Department of Defence/Phillip Cullinan)

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A study of colonial records held in the UK suggests that many more tsunamis have occurred in the Indian Ocean than once thought.

Australian natural hazards expert Dr Dale Dominey-Howes, from Macquarie University in Sydney, says he has come up with the most comprehensive evidence to date that at least five major tsunamis occurred in the region since 1819.

He says his preliminary research, which will be submitted for publication, should set alarm bells ringing for the region.

"There's definitely a risk and we need to get a much better handle on what that risk is," he says.

Dominey-Howes has recently returned from London where he scrutinised historical data from the India Records Office of the British Library on unusual flooding events since 1600.

The floods, some of which caused "several hundred deaths", were traditionally thought to have been caused by storms.

While admitting some eyewitness accounts may have been exaggerated, he says combined with meteorological, hydrological and marine records, it suggests the floods were in fact caused by earthquakes.

"There were floods recorded which were thought to be from storms but there were no tropical cyclones recorded at the time," he says.

"But they corresponded to records of earthquakes."

Dominey-Howes says apart from the well-documented 1883 Krakatoa tsunami that caused flooding in Java, Sumatra, the Andaman and Nicobar Islands and the Indian east coast, there have been earthquakes and associated large waves around Bombay (1819), the Andaman and Nicobar Islands (1881) and in the Arabian Sea (1945).

More recently, an Indonesian earthquake in 1977 caused waves 6 metres high at Cape Leveque 250 kilometres north of Broome on the Western Australian coast.

How will an early warning system cope?

Dominey-Howes' comments come after Indian Ocean nations seeking to build a tsunami early warning system agreed to move ahead with the scheme.

Some experts say the lack of a warning mechanism in the Indian Ocean was a factor in the more than 280,000 deaths that occurred after the earthquake off Indonesia caused a wave of tsunamis on Boxing Day.

Ministers from 43 countries affected by the 26 December tsunami recently met on the Thai island of Phuket to decide on a warning system, to be in place by 2006.

Australia wants a regional system co-ordinated by the UN's Intergovernmental Oceanographic Commission and has offered technical and warning experience based on its cyclone warning system, says parliamentary secretary to the environment minister Greg Hunt.

Hunt says Australia also needs to boost its domestic ability to deal with a tsunami, possibly through automatic text messaging alerts and home dialling.

But Dominey-Howes says public education is more important than a warning system.

He says the speed with which tsunamis can hit mean warning systems can only benefit communities at a distance from the quake's epicentre.